Purification of organic oxy-compounds



PURIFICATIQN F @BGANIC ()XY-fiOME'Q Richard Z. Moravec, Berkeley, and Theodore Evans and Cecil Eilumphreys, Martinez, Calla, assignors to Shell Development Corny. San Francisco, Calii., a corporation of Delaware No Drawing. Application dune 2d, 1935, at No. 28,182

. This invention relates to a process for the pu- Hitherto, no practical and economical methods rification of organic oxygen-containing comhave e p p for pu yin t alcohol pounds contaminated with oxidizable sulphurderivatives of the type herein described when containing p es. such compounds or their mixtures are contami- 5 The invention provides an economical and nated with relatively small amounts of oxidizable 5 hly effective method for the removal of obsulphur-containing compounds as hydrogen sul- J'ectionable sulphur-containing impurities from phide, carbonyl sulphide, mercaptans, carbon dinelltlal ic oxy-compounds which may be sulphide, thioethers, organic polysulphides, merconsidered as derivatives of the alcohols, said captides, and the like. Removal of the sulphur method comprising contacting the material to impurities has been attempted by subjecting the be purified with an alkaline compound capable of contaminated material to repeated rectifications oxidizing the sulphur impurities, or with an oxiand to treatments with concentrated sulphuric dizing agent, preferably under alkaline condiand other acids. These methods of purification tions, at a temperature below that at which have, however,-proved themselves to be unsatisthe organic oxy-compound is substantially defactory. They are, for the most part, ineiiicient stroyed as by oxidation, polymerization and/or in that only inorganic sulphur compounds are molecular condensation, for a time sufiicient to acted upon and, in addition, the conditions of oxidize the phur-containing impurities to intreatment necessary to effect substantial oxidaoxious or readily removable oxidized sulphur tion ofthe impurities are so vigorous and dif-' -30 bodies and, in the latter case, separating the flcult to control that the oxY-OO p underremovable oxidized sulphur bodies from th going purification is attacked and destroyed to treated material, preferably by distillation. such an extent that due to the loss in material In the manufacture of oxygen-containing orthe cost of purification is prohibitive. ganic compounds as ethers, esters, aldehydes, By our method, the objectionable sulphur-conketones, etc. from alcohols, which alcohols were taining impurities are oxidized to readily removin turn prepared from olefines or olefine-containable or inoxious sulphur bodies easily and ecoing gases as are obtained in the cracking of penomically under conditions at which substantialtroleum and petroleum products, the alcohol dely no destruction of the treated material by oxidarivatives are, in many cases, contaminated with tion, condensation or other means occurs.

: a small amounts of oxidizable sulphur compounds Our process is applicable with excellent rewhich, for the most part, are so difiicult to resuits to neutral oxygen-containing alcohol demove that the known methods of purification as rivatives of the class consisting of ethers, carby distillation are entirely inefiective. In genboxylic acid esters and the aldehydes and ketones.

eral, the presence of sulphur compounds in even The group of suitable compounds may for the very small amounts renders the alcohol derivasake of clearness and convenience be represented tives much less valuable. The sulphur compounds by the general formula R'.X, wherein R repp o them disagreeable d s i many resents an organic radical linked to X by means cases the oxy-compounds are unsuitable for many of a carbon atornand X represents one of the uses because of discoloration due to the sulphur groups- 012240011" or COR R representimpuritieswhen the y-compounds are used ing an organic radical linked to the O atom by 40 as intermediates in the preparation of other coma carbon atom, R. representing a metal or an pounds. compositions. sulphur mpur ties organic radical linked to the 0 atom by a carpresent in the raw material may render the rebo atom, and R represents hydrogen or an sultant product of much less value. In many organic radical l ked t the 0 atom by a carcases,'when the conversion. process involves cabon atom.

talysis with metal and metal-containing contact It is seen that the ethers may be represented bodies as silver, copper, nickel. cobalt, iron, etc.. by the formula R,-0--R' wherein R and R. may the sulphur compounds have a deleterious eifect be the same or different and represent alkyl, ar-

on the activity of the catalyst by poisoning the alkyl, alkenyl, aralkenyl, aromatic, alicyclic and same and inducing side reactions. heterocyclic radicals which may be substituted wherein R represents an organic radical linked to the CO group by a carbon atom and X represents hydrogen, an organic radical which may be the same or different than R, or the radical OR', B. representing an organic radical linked to the CO group by a carbon atom. R, R as well as the radical X when the compound is a ketone may represent alkyl, aralkyl, alkenyl, aralkenyl, aromatic, alicyclic and heterocyclic radicals which may be further substituted.

A group of suitable esters which are represented by the formula R-COO-R' includes among others compounds as methyl acetate, ethyl formate, ethyl butyrate, butyl isobutyrate, allyl acetate, isobutenyl acetate, the malonic acid esters, isopropyl acetate and the like and their homologues, analogues and suitable substitution products.

Our invention is particularly applicable to the purification of aldehydes and ketones. These compounds are represented by the formula R-CO-R' wherein R represents an organic radical linked to the 00 group by a carbon atom and R represents an organic radical which may be the same or difierent than R and which is linked to the CO group by a carbon atom, or hydrogen.

In the former case, the compound is a ketone while when R=H the compound is an aldehyde. Our inventionis of particular value as applied to the purification of aliphatic aldehydes and ketones derived from alcohols prepared by the sulphur compounds by our method.

' .trate solution added thereto.

hydration of olefines. For example, the aldehydes as formaldehyde, acetaldehyde, propionaldehyde, the butyraldehydes, the valeraldehydes and the like and the ketones as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone', methyl propyl ketone and the like as well as'their homologues, analogues and suitable substitution products may be substantially purified oi objectionable The method of the invention provides a very effective and economical means of purifying acetone contaminated with oxidizable sulphur compounds. A substantially sulphur-free acetone meeting alltrade requirements for pure acetone, and which is suitable for all uses to which acetone may be put, is readily obtained under conditions at which losses of the treated acetone are insignificant.

Acetone to be suitable for use in the manufacture of artificial silks as rayon and the like cellulose ether and ester materials is required to be free of sulphur compounds which will cause discoloration of an aqueousammoniacal silver ni- This extremely sensitive test for oxidizable sulphur compounds of sulphur compounds and obtain an acetone which passes the Celanese test, that is, does not ed under alkaline conditions.

aeeasse discolor an aqueous ammoniacal silver nitrate solution. 7

In the execution of our invention we employ those oxidizing agents capable of oxidizing the sulphur-containing impurities to inoxiousor readily removable sulphur bodies at temperatures and contact times at which destruction of the organic oxy-compound is substantially ob-v viated. A selected oxidizing agent may be employed per se or in solution or suspension in water or any other suitable medium. The oxidizing agent may be applied under neutral, slightly acidic or alkalineeonditions. It is to be understood that the use of destructive strong mineral acids as concentrated sulphuric, nitric, etc., is not contemplated.

The purification reaction is preferably execut- The oxidizing agent may of itself be alkaline, or it may be acidic or neutral. In the latter cases, it is preferably applied in the presence of water and an alkalineacting substance. We have found that under conditions of our invention the alkali-metal hydroxides in the solid state'act as oxidizing agents for some sulphur-containing impurities. -When' such impurities are present, the solid hydroxide in the form of pellets, granules, powder, etc., may be added to the material to be treated under conditions at which oxidation occurs, or the contaminated material may be passed in the vapor or gas phase over the solid oxidizing agent. For example, the material to be treated may be distilled through a column packed with pellets of an alkali-metal hydroxide.

Particularly suitable oxidizing agents, which i ammonium perchlorate, barium perchlorate, so-

dium perchlorate, cobalt perchlorate, etc.; the alkaliand alkaline earth metal hypohalites as sodium hypochlorite, potassium hypochlorite, sodium hypobromite, calcium hypochlorite, etc.; the more unstable organic hypohalites as the primary and secondary alkyl hypochlorites and 'hypobromites as ethyl hypochlorite,-'lsopropyl hypochlorite, secondary butyl hypochlorite, etc.

In some cases, the inorganic peroxides as sodium peroxide, barium peroxide and the like as well as the organic peroxides as ethyl hydrogen peroxide, diethyl peroxide, acetone peroxide, trlacetone peroxide, benzoyl peroxide and the like may be employed. The particular sulphur compound or compounds to be oxidized may be used as a basis for theselection oi an oxidizing agent of the requisite oxidizing power.

The halogen-containing oxidizing agents particularly the alkali and alkaline earth hypohalites, chlorates and perchlorates as well as the organic hypohalites are preferably employed as oxidizing agents. For-example, excellent results may be obtained byemploylng the relatively inexpensive and readily prepared sodium, potas- Lil ' sium and calcium hypochlorites as well as other can be determined by any of the well-known analytical methods. A test run will enable the operator to determine the optimum amount to use for eflicient and economical purification. The oxidizing agent may be used in amounts just sufiicient to oxidize the sulphur impurities or the oxidizing agent may be employed in excess. Generally, the use of a substantial excess is to be avoided since considerable deterioration of the treated material may result when the same is subsequently treated for removal of the oxidized sulphur bodies.

Although our invention is described with particular reference to the purification of organic oxy-compounds containing oxidizable sulphurv compounds, it is to be understood that the same may be applied to such oxy-compounds contaminated with other types of oxidizable impurities alone or in the presence of oxidizable sulphur compounds. For example, saturated organic oxycompounds as the ethers, aldehydes and ketones which contain as impurities, compounds as the readily oxidizable unsaturated aldehydes, ketones, alcohols, ethers, etc., may be substantially purified therefrom by our method. In many cases, under conditions at which the sulphurcontaining impurities are oxidized, other oxidizable impurities are also removed.

The invention may be executed in a variety of suitable manners. A preferred mode of operation comprises conducting the material to be treated to a suitable reaction vessel preferably so constructed that the contents may be agitated as mechanical stirring and heated under atmospheric or superatmospheric pressure or cooled as the particular operation may require.

If desired, the treatment may be eiiected in the kettle or" a distilling apparatus and the treated material distilled therefrom subsequent to the purification treatment. The treatment and the recovery of the treated material may be effected in separate vessels which may, if desired, be in communication with each other.

When distillation methods of recovering the purified material from the treated mixture are resorted to, the oxidized sulphur bodies, depending upon their nature may boil at a .higher or lower temperature than the purified material. In the -former case, they may be substantially separated by topping the mixture, the sulphur bodies being removed with the first fraction or fractions. In the latter case, the oxidized sulphur bodies will, for the most part. remain in the still as bottoms following distillation of the substantially pure material therefrom.

The oxidizing agent, per se or in solution or suspension in a suitable medium as water, may be added all at once or added to the material slowly, preferably with stirring. The temperature of the material is maintained sumciently low to avoid excessive oxidation of the wry-compound. Generally, we operate at temperatures of about 0., although higher and lower temperatures may be used when necessary or desirable. The mixture is allowed to stand for a period of time sufilcient to effect the desired oxidation of the sulphur impurities. The time of contact will vary with the nature and amount of the sulphur compounds present, the amount, concentration room temperature for about four hours.

and oxidizing power of the specific oxidizing agent employed, the temperature of operation and the efiiciency of the contacting of the reactants. Another suitable means of operating comprises introducing a solution or suspension of theoxidizing agent, in the required amount, into a conduit through which a turbulent fiow of the material to be treated is maintained. The size of the conduit, the rate of fiow of the material through it, and the amount andconcentration of the oxidizing agent may be so regulated that oxidation of the impurities is effected on one passage of the material through the conduit. .In this manner the impure material may be treated continuously while it is being conducted to a storage tank or to a purification stage, where the substantially pure material may be continuously recovered by distillation.

Lil

' After the material has been treated until the sulphur compounds are oxidized to the desired extent, the treated material may be directly rectified to efiect separation of the oxidized sulphur bodies or other means of eiiecting separation may be resorted to. When the material treated for removal of oxidizable sulphur compounds is in a substantially pure condition, it may not require efilcient fractionation to separate the pure material from the oxidized sulphur bodies. Topping oil or flashing ofi the material may be sufficient. If

an aqueous layer is present, said layer may be 3 separated prior to effecting distillation. When solid materials are present, the treated material may be filtered to chest their removal.

The following specific examples illustrate preferred modes of executing our invention. It is to be understood that it is not our intention to About 1.0 cc. of 1N NaOH solution and about 10 cc. of a 0.1N I2 solution were added to about 250 cc. of impure acetone which gave a positive Celanese test and had a'total sulphur content of about 0.001% as determined by the lamp method. The mixture was allowed to stand at At the end of this time the mixture was fractionated.

The fractionation yielded about 223 cc. of a substantially pure acetone which gave a negative Celanese test, that is, there was no discoloration, and by analysis contained less than 0.0005% sulphur. The oxidized sulphur bodies were for the most part left in the still as bottoms. bottoms contained about 0.0034% total sulphur as determined by the lamp method.

Example II About 1 gram of basic lead acetate was dissolved in about 20 cc. of water and the solution mixed with about 1000 cc. of acetone which gave a positive Celanese' test and had a total sulphur content of about 0.001%. The mixture was allowed to stand at about room temperature for about minutes. At the end of this time the mixture was charged to a suitable still and freetionated.

The first cut out of about cc. was discarded. The second and third cuts of about 400 cc. each, which contained 0.0003% and 0.0001% total sulphur, respectively, gave a negative Celanese test. The oxidized sulphur bodies were'for the most part present in the still as bottoms.

The;

Example III Three 1000 cc. portions of crude acetone contaminated with undesirable sulphur compounds were treated as below listed and the treated material distilled and tested.

Nature of treatment g gg i Percent Distilled-no treatment Positive... 0.

(blank) 0.5 gm. 1, and 5 cc. of 20% NaOH edded Negativo.. 0.008 2 gm. lead acetate added N egative.. 0. 0034 Example IV About 1000 cc. of a contaminated acetone which had a total sulphur content of about 0.0006% and which gave a positive Celanese test was charged to a-suitable reaction vessel and stirred at about room temperature while about 5 cc. of a sodium hypochlorite solution which contained about 0.35 gm. of NaOCl, and about 5 cc. of a 20% NaOH solution were added thereto.

After allowing a few minutes to insure complete reaction, the treated material was distilled. The following cuts were taken, tested and analyzed as follows:

Celanese Total sul out test phur Negative. Negative" 0. 0002% ,Negative" Less than Example V A crude sulphur contaminated acetone which gave a positive Celanese test and had a total sulphur content of about 0.0006% was flashed off, with no fractionation, through a distilling column packed with NaOH pellets. The condensed material gave a positive Celanese test and contained 0.0002% 5. l'his material was then fractionated in an ordinary fractionation apparatus.

The distillate was a substantially pure and sulphur free acetone. It gave a negative Celanese test, had a satisfactory color and odor and contained less than 0.0001% total sulphur by the lamp method.

' Example VI Celanese test -Negative Acidity None Color 0-5 KMnO test Negative Example :VII

About 1500 cc. of acetone which had been previously distilled was contacted with about 2 gm. of potassium persuiphate in aqueous solution and about 20 cc. oi a 1N NaOH solution. The mixture was stirred for a few minutes and then distilled. The distillate which was collected in a boiling range of from about 55 C. to 58 C. was tested. It gave a negative Celanese test and contained about 0.0002% total sulphur.

A crude contaminated acetone was treated under thesame conditions and using the same amounts of potassium pe'rsulphate and sodium hydroxide. The acetone obtained by distilling the treated material gave a negative Cclanese test and had a total sulphur content of about It will apparent to those skilled in the art to which this invention appertains that the same may be advantageously executed in a batch, in-' termittent or continuous manner. Purification may be effected inone or a plurality of stages in communication with one or more recovery stages in which the treated material may be continuously separated from the oxidized sulphur bodies by rectification or other means.

While we have described our invention in a detailed manner and provided specific examples illustrating suitable modes of executing the same, it is to be understood that modifications may be made and that no limitations other than those imposed by the appended claims are intended.

We claim as our invention:

1. A process for the purification of neutral organic oxygen-containing alcohol derivatives contaminated with oxidizable sulphur-containing impurities which comprises contacting the oxy-compound in the liquid phase with an oxidizing agent at a temperature and for a time adequate to oxidize the sulphur-containing impurities without substantially acting upon the organic oxy-compound.

2. A process for the purification of neutral organic oxygen-containing alcohol derivatives contaminated with oxidizable sulphur-containing impurities which'comprises contacting the oxycompound in the liquid phase with an alkaline oxidizing agent at a temperature and for a time adequate to oxidize the sulphurcontaining impurities without substantially acting upon the organic oxy-compound.

3. ,A process for the purification of neutral organic oxygen-containing alcohol derivatives contaminated with oxidizable sulphur-containing impurities which comprises contacting the oxy-compound in the liquid phase with an oxidizing agent in the presence of water at a temperature and for a time adequate to oxidize the sulphur-containing impurities without substantially acting upon the organic oxy-compound.

4. A process for the removal of oxidizable sulphur-containing impurities from neutral organic oxygen-containing alcohol derivatives which comprises contacting the liquid oxy-comvpound to be purified with an oxidizing agent at a temperature below that at which substantial destruction of the organic city-compound occurs, for atime and with the oxidizing agent present in an amount sufilcient to oxidize the sulphur impurities to readily removable oxidized sulphur bodies, and separating the oxidized sulphur bodies.

5. A process for the removal of oxidizable sulphur-oontaining' impurities from neutral organic oxygen-containing alcohol derivatives of the class consisting of ethers, esters, aldehydes and ketones which comprises contacting the liquid oxy-compound to be purified with an oxidizing agent under alkaline conditions at a temperature below that at which substantial destruction of the organic oxy-compound occurs, for a timeand with the oxidizing agent present in an amount sufiicient to oxidize the sulphur impurities, and separating the oxidized sulphur bodies.

6. A process for the removal of oxidizable sulphur-containing impurities from organic ethers which comprises contacting the liquid ether to be purified with an oxidizing agent under alkaline conditions at a temperature below that at which substantial destruction of the ether occurs, for a time and with the oxidizing agent present in an amount sufiicient to oxidize the sulphur impurities, and separating the oxidized sulphur bodies.

'7. A process for the purification of neutral alcohol derivatives of the class consisting of ethers,

esters'aldehydes and ketones which are contaminated with oxidizable sulphur-containing impurities which comprises contacting the material to be purified, in the liquid phase with an aqueous alkaline solution of a halogen at a temperature below that at which substantial destruction of the organic oxy-compound occurs, for a time suiiicient to oxidize the sulphur-containing impurities. I

8. A process for the purification of an aldehyde contaminated with oxidizable sulphur-containing impurities which'comprises contacting the aldehyde in the liquid phase with an oxidizing agent under alkaline conditions at a temperature below that at which substantial destruction of the aldehyde occurs, for a time suflicient to oxidize the sulphur containing impurities.

9. Aprocess for the purification of a ketone contaminated with oxidizable sulphur-containing impurities which comprises contacting the ke-- tone in the liquid phase with a hypohalite under alkaline conditions at a temperature below that at which substantial destruction of the ketone occurs, for a time suflicient to oxidize the sul-' phur-containing impurities.

10. A process for the purification of a ketone contaminated with oxidizablesulphur-containing impurities which comprises contacting the ketone in the liquid phase with a hypohalite 01 an alkali-forming metal underalkaline conditions in the presence of water at a temperature below that at which substantial destruction of the ketone occurs, for a time suflicient to oxidize the sulphur-containingimpurities.

11'. A process for the purification of a ketone contaminated with oxidizable sulphur-containing impurities which comprises contacting the ketone in the liquid phase with a solid alkali-metal hydroxide at a temperature and for a time sufficient to oxidize the sulphur-containing impurities while leaving the ketone substantially unaffected,

12. A process for the purification of acetone v.contaiiiinated with oxidizable sulphur-containing impurities which comprises contacting the acetone in the liquid phase with an oxidizing agent a'tia' temperature below that at which substan tial destruction of the acetone occurs, for a tim sufficient to oxidize the impurities.

*13; A process for the removal of oxidizable sul-. phur-containing impurities from acetone which comprises contacting the acetone in the liquid phase with a solid alkali-metal hydroxide at a the liquid phase with an amount of an aqueous alkaline solution of sodium hypochlorite suflicient to oxidize the impurities at a temperature below that at which substantial destruction oi. the acetone occurs, for a time 'sufiicient to oxidize the sulphur-containing impurities, and distilling the treated material to separate the oxidized sulphur bodies.

16. A process for the purification of a ketone containing oxidizable sulphur-containing impurities in an amount sufficient to discolor an aqueous ammoniacal silver nitrate solution but insufficient to impart a disagreeable odor to the ketone which comprises treating the ketone in the liquid phase with an oxidizing agent for a time and at a temperature sufiicient to oxidize the impurities without effecting substantial destruction of the ketone, and distilling the mixture whereby the oxidized sulphur bodies are separated and a ketone which will not discolor an aqueous ammoniacal silver-nitrate solution is obtained.

17. A process for the purification of acetone containing oxidizable sulphur-containing impurities in an amount suihcient to discolor an aqueous ammoniacal silver nitrate solution but insufflcient to impart a disagreeable odor to the acetone which comprises treating the acetone in the liquid phase with an oxidizing agent under alkaline conditions for a time and at a temperaturesuflicient to oxidize the impurities without effecting substantial destruction of, the acetone,

and distilling the mixture whereby the oxidized sulphur bodies are separated and acetone which will not discolor an aqueous ammoniacal silver nitrate solution is obtained.

18. A process for the purification of acetone containing 'oxidizable sulphur-containing impurities in an amount sufficient to discolor an aqueous ammoniacal silver nitrate solution but insufficient to impart a. disagreeable odor'to the acetone which comprises treating the acetone in the liquid phase with an amount of an aqueous alka-' line solution 01 an alkali-metal hypohalite not substantially in excess of that required to oxi- -dize the impurities, for a time and at a temperature adequate to oxidize the impurities without eflecting substantial destruction oi the acetone, and distilling the treated mixture whereby the oxidized sulphur bodies are separated and acetone which will not discolor an aqueous ammoniacal silver nitrate solution is obtained.

RICHARD Z. MORAVEC. THEODORE EVANS. CECIL BUMPHREYS. 

